The present invention relates to a turbine housing of an exhaust gas turbocharger.
Internal combustion engines, in particular those used in motor vehicles are increasingly charged by fluid kinetic machines in order to further increase performance and with this lower fuel consumption. Preferably, turbochargers are used as fluid kinetic machines. The turbocharger, and in particular the housing of the turbocharger are adjusted very accurately to the performance characteristic of the respective engine.
In order for the turbocharger to operate with a high performance, it is very important to ensure exact clearances between individual components of the turbocharger before, during and after operation. In between the individual operating states, temperature differences of up to several 100° C. occur which result in different expansions in the different components and used materials and material thicknesses. In case of expansion, the clearances also change so that an undesired blowby may occur within the turbocharger. This causes a reduction of the performance of the turbocharger. Also, components may come into contact with each other due to different expansions. In a worst case, collisions of the components occur, which cause damage to or a total failure of the turbocharger.
Further, the weight reduction of all materials and components used in motor vehicle construction is very important. Here, a turbocharger, in particular a housing of a turbocharger constructed from sheet metal is sought to be produced particularly lightweight.
DE 100 22 0 52 A1 proposes the de-coupling of exhaust gas conducting components and to support or seal outer structures. While the exhaust gas conducting components of the turbocharger are exposed to high thermal stress, so that as to glow, the thermal stress on the sealing outer structures is significantly smaller. However, the outer housing, in particular in the areas of the connection to the bearing housing of a turbocharger and also at the inlet sides of the relatively hot exhaust gas are also exposed to very high thermal flow technical stresses.
The outer housing of a turbocharger generally consists of formed sheet metal shells which are usually welded together with bearing flanges using thermal joining. Also coupled to the bearing flanges is an inner housing of the exhaust gas turbocharger.
Usually, the inner housings rest against the bearing flanges or are additionally materially bonded to the bearing flanges. When the inner housing rests against the bearing flanges, an incomplete sealing and with this blowby may occur due to the different coefficients of thermal expansion. In case of a bonding coupling, the zone impacted by heat during the thermal joining process is geometrically and materially weakened by the thermal joining process. At this point, fatigue fractures or cracks may form in case of extreme stresses.